title: Electrically controllable liquid crystal random lasers below the Fréedericksz transition threshold.
abstract: This investigation elucidates for the first time electrically controllable random lasers below the threshold voltage in dye-doped liquid crystal (DDLC) cells with and without adding an azo-dye. Experimental results show that the lasing intensities and the energy thresholds of the random lasers can be decreased and increased, respectively, by increasing the applied voltage below the Fréedericksz transition threshold. The below-threshold-electric-controllability of the random lasers is attributable to the effective decrease of the spatial fluctuation of the orientational order and thus of the dielectric tensor of LCs by increasing the electric-field-aligned order of LCs below the threshold, thereby increasing the diffusion constant and decreasing the scattering strength of the fluorescence photons in their recurrent multiple scattering. This can result in the decrease in the lasing intensity of the random lasers and the increase in their energy thresholds. Furthermore, the addition of an azo-dye in DDLC cell can induce the range of the working voltage below the threshold for the control of the random laser to reduce.
authors.affiliation: Institute of Electro-Optical Science and Engineering and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan. crlee@mail.ncku.edu.tw
authors.forename: Chia-Rong
authors.initials: CR
authors.lastname: Lee
authors.forename: Jia-De
authors.initials: JD
authors.lastname: Lin
authors.forename: Bo-Yuang
authors.initials: BY
authors.lastname: Huang
authors.forename: Shih-Hung
authors.initials: SH
authors.lastname: Lin
authors.forename: Ting-Shan
authors.initials: TS
authors.lastname: Mo
authors.forename: Shuan-Yu
authors.initials: SY
authors.lastname: Huang
authors.forename: Chie-Tong
authors.initials: CT
authors.lastname: Kuo
authors.forename: Hui-Chen
authors.initials: HC
authors.lastname: Yeh
mesh_terms: D017076:Computer-Aided Design; D004574:Electromagnetic Fields; D004581:Electronics / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007834:Lasers; D050866:Liquid Crystals / Q000737:chemistry* / Q000528:radiation effects*